Summary: The viral protein responsible for initiating viral infection of filoviruses has been shown to be the glycoprotein (GP). We plan to use alanine-scanning mutagenesis to introduce mutations in the GP cDNAs for both the Marburg and Ebola strains of filovirus. Retroviral pseudotypes bearing control or mutated filovirus glycoproteins (GPs) will be used to assess the effect of these mutations on viral tropism and entry. The goal of this study is to identify an epitope on the filovirus GP that is necessary to facilitate viral entry. Identification of such a domain may then allow for subsequent rational design of agents that may inhibit filovirus infection. We only received the reagents to initiate work on this project in July, 2002, so it is too early to provide a summary of any results at this time.